The invention relates to couplings in general, and more particularly to improvements in couplings which can be used to sealingly and separably connect an end portion (e.g., a nipple) of a first tubular component (such as a metallic or plastic pipe) with an end portion of a second tubular component (e.g., an elastic hose of rubber or plastic material). Still more particularly, the invention relates to improvements in couplings of the type wherein a sleeve-like tubular coupling member has a circumferentially complete tubular section which is insertable into the end portion of the second component and one or more prong-like flexible coupling elements which engage an external retainer of the end portion of the first component in assembled condition of the coupling. Such couplings are normally further provided with one or more sealing elements which are interposed between the end portion of the first component and the internal surface of tubular section of the tubular coupling member, and with means for clamping the end portion of the second component against the exterior of the tubular section.
Commonly owned U.S. Pat. No. 4,775,173 to Sauer discloses a hose coupling wherein the tubular coupling member is made of a plastic material and its tubular section is integral with elastically deformable prong-shaped coupling elements. The nipple of the pipe which is to be sealingly connected with an end portion of a flexible hose has an external rib with a frustoconical flank serving as a means for spreading the coupling elements apart during introduction of the nipple into the tubular section. When the nipple is properly inserted into the tubular coupling member, the prongs engage a radially extending flank of the rib and thus prevent accidental extraction of the nipple in assembled condition of the coupling.
A drawback of the patented coupling is that a rather strong force is required to spread the prongs apart during assembly of the coupling because the rib at the exterior of the nipple deflects only a small component of the axially applied force in the radial direction of the nipple. The situation is aggravated if the prongs are made of a relatively stiff resilient material which offers a pronounced resistance to elastic deformation.